MR-guided laser-induced thermotherapy in recurrent extrahepatic abdominal tumors

The aim of this study was to evaluate the feasibility of MR-guided laser-induced thermotherapy (LITT) for treatment of recurrent extrahepatic abdominal tumors. In 11 patients (6 women and 5 men; mean age 53 years, age range 29-67 years) with 14 lesions the following tumors were treated in this study: paravertebral recurrence of hypernephroma (n=1); recurrence of uterus carcinoma (n=1); recurrence of chondrosarcoma of the pubic bone (n=1); presacral recurrence of rectal carcinoma (n=1); recurrent anal cancer (n=1); metastases in the abdominal wall (n=1); and lymph node metastases from colorectal cancer (n=8). A total of 27 laser applications were performed. A fast low-angle shot 2D sequence (TR/TE/flip angle=102 ms/8 ms/70 degrees ) was used for nearly real-time monitoring during treatment. All patients had no other treatment option. Seventeen LITT sessions were performed using a conventional laser system with a mean laser power of 5.2 W (range 4.5-5.7 W), and 10 LITT session were performed using a power laser system with a mean laser power of 28.0 W. In 10 lesions total destruction could be achieved. In the remaining recurrent tumors, significant reduction of tumor volume by 60-80% was obtained. All patients tolerated the procedure well under local anesthesia. No complications occurred during treatment. Laser-induced thermotherapy is a practicable, minimally invasive, well-tolerated technique that can produce large areas of necrosis within recurrent tumors, substantially reducing active tumor volume if not resulting in outright destruction of tumor.     

Invited. MRI of laser-induced interstitial thermal injury in an in vivo animal liver model with histologic correlation

Laser-induced interstitial thermal therapy (LITT) is a preferred method of minimally invasive therapy. MRI is a noninvasive method by which to monitor the thermal effects of LITT. To properly control such effects, changes in MRI parameters during and after LITT should be correlated with changes in the tissue. T1-weighted fast spin echo (FSE) MRI (1 image/10 seconds) at 1.5 T monitored LITT in vivo in rabbit liver (n = 6) using an interstitial bare delivery fiber (600-μm diameter; 3.0 W; 1,064 nm; 150 seconds). During laser irradiation, MRI signal intensity decreased around the fiber tip; after irradiation, this hypointensity proved reversible and permanent lesions were evident. The lesions had hyperintense margins that were brighter than surrounding normal tissue (P < .001); the tissue in these bright regions was mapped to tissue necrosis characterized by the presence of thermally damaged ghost red blood cells amid generally normal hepatocytes. T1-FSE identified the spatial extent of the LITT lesions.     

Preliminary clinical experience with laser-induced interstitial thermotherapy in patients with hepatocellular carcinoma

The purpose of this preliminary study was to evaluate whether laser-induced interstitial thermotherapy (LITT) may be used for palliative treatment of localized hepatocellular carcinomas (HCC). We applied LITT to two patients suffering from unresectable localized hepatocellular carcinomas of different sizes (2.5 and 4 cm). LITT was performed with an Nd:YAG laser (1,064 nm) at 5 W laser power (15–20 minutes). Thermometry during LITT was performed by MRI using a temperature-sensitive T1-weighted fast low-angle shot (FLASH) sequence. Follow-up for local tumor control was performed by MRI and ultrasound. LITT was well tolerated and no adverse events occurred during or after LITT; no secondary liver lesions were seen in the follow-up (11 or 12 months, respectively). Only minimal tumor growth was observed in the larger HCC (from 4 to 5 cm), whereas the smaller HCC remained unchanged in size during 11 months of follow-up. We conclude that LITT might be an effective minimally invasive palliative treatment option for patients with small unresectable HCC.     

Radiofrequency ablation of osseous metastases for the palliation of pain

A number of different methods have been proposed for pain relief in cancer patients with bone metastases, each with different indications, contraindications and complications (systemic analgesics, bisphosphonates, antitumor chemotherapy, radiotherapy, systemic radio-isotopes, local surgery and vertebroplasty). The ideal treatment has to be fast, safe, effective and tolerable for the patient. CT-guided radiofrequency (RF) ablation may fulfill these criteria. Our experience in the treatment of 30 patients (34 lesions) with painful bone metastases using RF ablation was assessed. There was a significant decrease in the mean past-24-h Brief Pain Inventory (BPI) score for worst pain, for average pain and for pain interference during daily life (4.7, 4.8 and 5.3 units respectively) 4 and 8 weeks after treatment. There was a marked decrease (3 out of 30 patients 4 and 8 weeks after treatment) in the use of analgesics. CT-guided RF ablation appears to be effective for treatment of painful bone metastases.     

Laser-induced thermotherapy (LITT) of liver metastases: MR-guided percutaneous insertion of an MRI-compatible irrigated microcatheter system using a closed high-field unit

PURPOSE: To evaluate the efficacy and safety of a new MRI-compatible irrigated laser microcatheter system for thermal ablation of liver metastases. MATERIAL AND METHODS: The new microcatheter system consists of a titanium needle with a diameter of 1.5 mm and a surrounding Teflon catheter with an outer diameter of 1.8 mm (5.5 F). In vitro laser-induced coagulation of bovine liver tissue was performed to determine the optimal perfusion rate of cooling saline flow, maximum laser energy, and ablation time. Laser-induced thermotherapy using the new microcatheter system, an Nd:YAG laser (Dornier), and a flexible laser light guide (Somatex GmbH, Berlin, Germany) was performed in 28 patients with liver metastases. Percutaneous insertion and positioning of multiple microcatheters in the lesion and monitoring of therapy was performed with a closed high-field MRI scanner using T1-weighted gradient-echo sequences during breath-hold. RESULTS: A perfusion rate of 0.75 mL/minute, a laser energy of 15 W, and an ablation time of 20 minutes were found suitable to achieve safe and sufficient ablation of metastatic tissue. The mean volume of induced coagulation in vitro was 23.9 mL. Ablation of liver metastases in patients was technically and clinically successful. CONCLUSION: The new microcatheter system allows for both catheter placement and monitoring of therapy using a single imaging modality. This shortens the procedure and enables more precise puncture and therapy of liver metastases. Due to the miniaturized design of the catheter and the real-time monitoring, the procedure is minimally invasive and very well tolerated by patients. This new technique seems to be a safe and feasible alternative in treating liver metastases.     

Simulations of thermal tissue coagulation and their value for the planning and monitoring of laser-induced interstitial thermotherapy (LITT).

MRI information is widely used for the monitoring of thermal therapies, such as laser-induced interstitial thermotherapy (LITT). However, a detailed knowledge about the relationship between time/temperature exposure and resulting tissue thermal damage is needed to estimate the lesion extent. The aims of this work were to model the thermal response of laser-irradiated tissue and to assess the value of Monte Carlo simulation (MCS) for tumor therapy planning and monitoring. MCS yielded true 3D distributions of laser-induced temperature and thermal damage. These results were compared with 2D MR thermometry data from in vitro experiments performed on animal liver tissue over an ordinary range of laser powers (10-25 W) and irradiation times (5-25 min). Clinical reference data were available from MR-guided liver LITT procedures. MCS correctly predicted the shape of temperature and damage distributions. The quantitative agreement between simulated and measured lesion diameters was within 10% and 15% for the in vitro and in vivo cases, respectively. The simulated 53 degrees C isotherm best estimated the boundary of the final thermal damage (6% variance). This study shows that MCS of interstitial laser coagulation provides unique information that can be of use in the empirical correlation of temperature with thermal damage, and can assist greatly in thermal treatment planning and monitoring.     

MR引导下激光间质热疗的原理及临床应用

介绍激光间质热疗的基本原理及MR导引的优势—无创性测温、避免电离辐射危险、优良的组织分辨率、良好的血管可视性、任意平面和方位的扫描提供三维信息等。并探讨MR引导下激光间质热疗临床应用价值     

Radiofrequency ablation of lung metastases: factors influencing success

This paper analyses the factors associated with successful radiofrequency ablation (RFA) of lung metastases. The study group comprised 37 patients [19 female, mean age 61 (34–83)] with 72 metastases who had follow-up CT scans available for analysis and for those with no recurrence >6 months follow-up. Internally cooled electrodes were used in 64 and expandable electrodes in 8. The tumour size and location, electrode type, number of ablations, duration of ablation, year of treatment and tumour contact with vessels larger than 3 mm were recorded. The mean tumour diameter was 1.8 cm (0.4–6.6 cm). Mean follow-up in those without recurrence was 13.1 months (6–48). Recurrence was common in larger tumours, occurring in 7/7 (100%) tumours >3.5 cm compared with 18/65 (28%) ≤ 3.5 cm (P < 0.01). Recurrence occurred in 14/24 (58%) tumours in direct contact with large vessels compared with 11/48 (23%) of the remainder (P = 0.04). On multivariate analysis, size was the dominant feature (P = 0.013); vessel contact and peripheral location did not reach significance (P = 0.056 and 0.054 respectively). Peripheral tumours less than 3.5 cm with no large vessel contact are the optimal tumours for RFA.     

Laser-induced interstitial thermotherapy of liver metastases in an interventional 0.5 Tesla MRI system: technique and first clinical experiences

Laser-induced interstitial thermotherapy (LITT) surveyed by magnetic resonance imaging (MRI) has been shown to be effective in various applications. The laser treatment of colorectal liver metastases usually requires a separate device (e.g., ultrasound or CT) to position the laser applicator. In this study, we used an interventional 0.5 T MRI system, allowing both the navigation to the target tissue and on-line thermometry. Laser irradiation was performed using a near-infrared laser source combined with a cooled laser light guide. We treated 20 patients exhibiting a total of 58 colorectal liver metastases. Clinically relevant complications did not occur. No residual tumor was observed after laser irradiation in all metastases with a diameter below 2 cm. Metastases with a mean diameter between 2 and 3 cm demonstrated total necrosis in 71%, while in larger tumors this proportion decreased to 46% (diameter, 3-4 cm) and 30% (diameter, >4 cm), respectively. We conclude that LITT, guided by the employed interventional MRI system, is feasible and safe. The results suggest a more aggressive treatment, especially for larger metastases. J. Magn. Reson. Imaging 2001;13:729-737.     

Adrenal neoplasms: Effectiveness and safety of CT-guided ablation of 23 tumors in 22 patients

Purpose

To retrospectively evaluate the effectiveness and safety of image-guided ablation of adrenal tumors.

Materials and methods

: This HIPAA-compliant study was IRB approved and informed consent was waived. From 5/1999-6/2008, 20 consecutive adrenal metastases (mean diameter 4.2 cm; range, 2–8) and 3 hormonally active primary adrenal tumors (mean diameter 2.3 cm; range, 1–4), including an aldosteronoma and 2 pheochromocytomas in 22 patients (14 men, 8 women; mean age 61 years; range 40–84) were ablated in 23 sessions. Bilateral metastases were treated in a single patient. Radiofrequency ablation was used to treat 16 adrenal metastases and the 3 hyperfunctioning tumors. Microwave ablation was used to treat 4 metastases.Successful treatment was defined as a lack of both enhancement on follow-up contrast enhanced CT and/or up-take on FDG PET-CT and for functioning tumors, resolution of biochemical abnormalities.

Results

Technical success was achieved in all sessions. Mean follow-up was 45.1 months (range, 1–91) Local tumor progression (focal enhancement at ablation site ≥1 cm in short axis) was detected in 4 of 23 tumors, two of which were identified bilaterally in a single patient prompting re-treatment. Of 19 patients with metastatic disease, 16 had fatal extra-adrenal disease progression, and 3 remain alive. Two of the 3 patients who underwent ablation of hyperfunctioning tumors remain alive, including the patient with an aldosteronoma who had recurrent symptoms 91 months post ablation. Intra-ablative hypertension occurred in 9% (2/23) of sessions and was successfully treated pharmacologically.

Conclusion

Ablation of metastatic and hyperfunctioning adrenal tumors is safe and may provide local control and treatment of pathologic biochemical activity.     

Invited. Predictability of the size of laser-induced lesions in T1-weighted MR images obtained during interstitial laser-induced thermotherapy of benign prostatic hyperplasia

The purpose of this study was to predict diameters of lesions induced by laser-induced thermotherapy (LITT) of benign prostatic hyperplasia (BPH) from MRI signal/tissue temperature correlations during on-line monitoring with a temperature-sensitive fast low-angle shot (FLASH) sequence. Twenty LITT procedures with Nd:YAG (1,064 nm) and diode (830 nm) lasers were monitored on line with a T1-weighted FLASH sequence at 1.5 Tesla. Interstitial prostate temperature (T) was measured on line in 10 LITT procedures and laser energy deposition in 12. Slopes of linear regression curves for signal intensity (SI) over T were applied to determine SI at 60°C to estimate diameters of intraprostatic LITT lesions. Diameters of unperfused LITT lesion cores in contrast-enhanced T1-weighted images served as gold standards. Linear regression curves with an average slope of ?.54% SI/°C were obtained in 17 LITT procedures. Correlation coefficients were r = .92?.95 for SI/T and SI/energy deposition. Baseline variation of SI at body temperature was ±3.9%, corresponding to ±7°C. Prediction of size (13 lesions) from on-line FLASH imaging was correct in 10 of 13, whereas 3 lesions were overestimated. Prediction of LITT lesion diameters from on-line MRI monitoring is possible with a temperature-sensitive FLASH sequence in the prostate. Accuracy may suffice to assign target regions of interest to tissue locations to be protected from coagulation.     

Treatment planning for MRI-guided laser-induced interstitial thermotherapy of brain tumors—The role of blood perfusion

MR techniques have been demonstrated to allow a reliable monitoring of laser-induced interstitial thermotherapy (LITT). However, an adequate on-line control of this coagulation technique requires an exact therapy planning. The latter is mandatory to interpret the MR-monitoring data correctly to guarantee a precise laser irradiation. Moreover, it is a prerequisite for online decisions if modifications of the therapeutic regimen are required. In this work, we present a new simulation technique for LITT planning. The model accounts for the specific geometry of the treatment site, the exact configuration of the applicator, and the optical and thermal properties of the tissue, including changes during the heating process. The simulation results were compared with MR scans of laser-induced lesions in three patients with World Health Organization (WHO) grade II astrocytoma. Special interest was directed toward the role of blood perfusion, which was studied parametrically. Good agreement between the simulation results and the MR data was found if the appropriate blood perfusion rates were taken into account. Thus, the model can generate valid therapy plans allowing a precise on-line control of laser irradiation using MR techniques. Neglecting adequate perfusion parameters resulted in substantial errors with respect to the prediction of the final laser lesion.     

Liver metastases of neuroendocrine carcinomas: interventional treatment via transarterial embolization, chemoembolization and thermal ablation

The aim of this review article is to provide a practical clinical guideline for indication, technical aspects, protocol guideline and strategies for the interventional treatment of liver metastases from neuroendocrine tumors and focusing on the results of various protocols of management. The response to therapy, in the published articles, is calculated on the basis of the following clinical parameters; including symptomatic response (SR), biologic response (BR), morphological response (MR), progress free survival (PFS), and survival periods (SP). Transarterial chemoembolization (TACE) has been associated with SR rates of 60-95%, BR of 50-90%, MR of 33-80%, SR of 20-80 months, and a 5-year survival of between 50% and 65%. PFS was also between 18 and 24 months. In the transarterial embolization (TAE) group, SR was similar to the TACE group, MR was 32% and 82%, survival was between 18 and 88 months with a survival rate of 40-67%, and BR was between 50% and 69%. Radiofrequency ablation (RFA), either percutaneous or during surgery, has been associated with SR of 71-95% for a mean duration of 8-10 months, BR of 65%, and mean SP of 1.6 years after ablation. The mean survival following surgical resection for operable cases is 4.26 years ± S.D.: 1.1.

Conclusion

The interventional protocols for the management of liver metastases from neuroendocrine tumors: for oligonodular liver metastatic deposits, local resection or RFA and/or LITT is recommended, while in multinodular diseases with higher tumor load, TACE or TAE is recommended.     

Preliminary experience with the application of Gadolinium-DTPA before MR imaging-guided laser-induced interstitial thermotherapy of brain tumors

The purpose of this study was to investigate the potential value of i.v. gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) applied before MRI-guided laser-induced interstitial thermotherapy (LITT) of brain tumors without original enhancement, especially in defining total lesion size during therapy. MRI-guided LITT was performed on two patients with astrocytoma WHO II. For both patients, Gd-DTPA was administered intravenously after a first irradiation period and LITT was continued after pulling back the light guide to coagulate the upper parts of the tumor. In both patients, the whole irreversible damaged zone of the second irradiation period after Gd-DTPA showed an intense increase of signal intensity. The spatial expansion correlated with the diameter of an enhancing rim after Gd-DTPA on follow-up studies. Our preliminary results indicate that the application of Gd-DTPA before MRI-guided LITT may be of value in defining exactly the size of the irreversible damaged zone during therapy in nonenhancing brain tumors.     

Invited. In vivo MRI thermometry using a phase-sensitive sequence: Preliminary experience during MRI-guided laser-induced interstitial thermotherapy of brain tumors

The purpose of this study was the application of the proton-resonance-frequency method to monitor laser-induced interstitial thermotherapy (LITT) in a patient with an astrocytoma WHO II. A phase-sensitive two-dimensional (2D) fast low-angle shot (FLASH) sequence was used to determine the temperature-related phase shifts during LITT. Temperature maps were displayed during therapy with a temporal resolution of 20 seconds. Irradiation was discontinued as soon as the 60 to 65°C isotherm reached the margin of the tumor. A contrast-enhanced MRI study performed immediately after therapy showed a good correlation of the size of an enhancing rim around the lesion with the 60 to 65°C isotherm. The preliminary results of our study indicate that MRI guidance of LITT may be improved by temperature quantification based on the proton-resonance-frequency method.     

Primary lung cancer: treatment with radio-frequency thermal ablation

Primary lung cancer is the most frequently diagnosed malignancy in the world and the leading cause of death from cancer [1]. When the initial diagnosis is made, most cases are inoperable or the patients condition does not permit surgical interventions [2]. For patients with inoperable lung cancer, percutaneous radio-frequency thermal ablation (RFA) under CT guidance represents an alternative and minimally invasive treatment. It can also be applied in combination with radiation therapy and chemotherapy. We report three cases treated by percutaneous CT-guided RF ablation, from which two had post-operative recurrent tumor and one was inoperable.     

射频消融技术临床应用现状

射频消融技术是一种安全、有效、微创治疗实体肿瘤的新方法,现广泛用于治疗原发性和转移性肝癌,特别是小肝癌.设备的进展和联合疗法使射频消融成为治疗大肝癌的有效手段.近期又被用于治疗骨骼、肾、肾上腺、肺、乳腺、甲状腺等部位的肿瘤.本文综述了射频消融的原理和临床应用现状并对其疗效进行评价.     

MRI引导下激光导热疗法处理动物正常肝脏所致病灶的MR与病理学比较研究

目的：MRI引导下激光导热疗法（LITT）处理动物正常肝脏，判断病灶MRI实时信号反映病理结果的准确性。方法：新鲜猪肝20个，按处理方式不同分为2W 10min、4W2.5min、4Wmin、4W7.5min、8W2.5min5个组，每组4个。在开放私MR仪上，于射频扰相稳态采集反转梯度回波（radiofrequency spoiled steady state acquisiton with rewound gradient echo,RSSG)序列下LITT处理猪肝，监测病灶MRI信号变化至术后5min，对病灶大体直径和术后即刻（术后0min）及5min时MRI信号直径进行比较，并观察MRI信号与病理结果的关系。结果：每组中LITT大体病灶与相应MRI信号直径比较采用配对t检验：（1）LITT病灶大体直径与术后实时MRI信号直径比较，t值分别为1．095、0．792、0．775、0．000、0．522，P值均＞0．05，统计学上差异无显著性意义，在病理上病灶大体和镜下表现与实时MRI信号存在着对应关系；（2）LITT病灶大体直径与术后5minMRI信号直径比较，t值分别为14．000、5．019、19．053、3．434、16．189，P值均＜0．05，统计学上差异有显著性意义。结论：MRI引导下LITT处理正常猪肝MRI实时信号可以反映实际病灶的变化。MRI引导下LITT可能成为治疗局部和区域性肿瘤的1种有效手段。     

Radiofrequency Ablation of Renal Tumors: Four-Year Follow-Up Results in 47 Patients

Objective

To retrospectively evaluate the intermediate results of radiofrequency ablation (RFA) of small renal masses (SRMs).

Materials and Methods

Percutaneous or laparoscopic RFA was performed on 48 renal tumors in 47 patients. The follow-up studies included a physical examination, chest radiography, creatinine level, and contrast-enhanced CT or MRI. To confirm the pathologic criteria of complete ablation, 35 patients underwent a follow-up biopsy. Recurrence was defined as contrast enhancement on imaging studies after 3 months, lesion growth at subsequent imaging, or viable cancer cells on follow-up biopsy.

Results

Technical success was achieved in 43 (89.6%) of 48 renal tumors. The mean tumor size was 2.3 cm and the mean follow-up period was 49.6 months. Repeated RFA was necessary in 5 tumors due to incomplete ablation. The overall complication rate was 35.8%, of which 96.2% were mild complications. Serum creatinine levels at 12 months after RFA did not differ from those before RFA (1.28 vs. 1.36 mg/dL). Four patients were found to have recurrence at various follow-up intervals, and distant metastasis was not found in any cases.

Conclusion

RFA appears to be a useful treatment for selected patients with SRMs. Our 4-year follow-up results disclose an excellent therapeutic outcome with RFA, while achieving effective local tumor control.     

Palliation of Painful Perineal Metastasis Treated with Radiofrequency Thermal Ablation

We report a case of painful perineal metastasis from urinary bladder carcinoma in a 73-years-old woman, treated with CT-guided radiofrequency ablation (RFA). The pain was immediately relieved and follow-up at 1 and 6 months showed total necrosis of the mass. One year later, the patient has no pain and her quality of life is improved.